What is causing this grief!
 

I have a decent 85 911 with the 3.2 engine. The only upgrade has been the installation of a chip. The car runs great-no starting problem, good idle, pulls strong to 6000 rpm. Car shows 113,xxx miles. I had a smog check done before the chip install, and it passed with flying colors.

Because of the problem described below I had a compression and leak down test done yesterday. No appreciable leak down and all cylinders show 165-170 compression.

The oxygen sensor was completely inoperable and we put in a new one.

The car has no smoke at start up. However, when driving the car at a sustained rpm, 2500-3500, for a period of time (30 minutes) and coming to a stop or red light the car will belch out blue/black smoke and the smell is very oily. It will not do this at every stop.

I have had 2 Porsche repair facilities check the car and they both seem to think the intermittent smoking is being caused by the chip. I did retain the factory chip.

ALthough the car passed smog 6 weeks ago it will not pass now.
C/O reads 4 percent and H/C are above 400 ppm.

What is going on?

Larry Harris

Too much oil in the sump?

Best,
Grady

>The car has no smoke at start up. However, when driving the car at a >sustained rpm, 2500-3500, for a period of time (30 minutes) and >coming to a stop or red light the car will belch out blue/black smoke >and the smell is very oily. It will not do this at every stop.


Sound just like my car used to be. I had worn valve guide seals. When one pulls off the highway, one tends to coast with the engine in gear, still at 2-3k rmp, and the throttle at idle. This creates a high vacuum in the intake manifold which sucks oil down the valve guides. When the car stops, the smoke starts.

As you already know, blue means oil. So oil is getting into the combustion chamber one way or another. If the oil's not overfilled then I'd think about valve guides.

Just a thought.

Contrary to my worst expectations I believe I have found the source of my smoke problem. This morning I changed the aftermarket chip back to the original. I then dove the car for over an hour, both on the freeway system (80-85mph), and stop and go city traffic.

NO MORE SMOKE!!!


The aftermarket chip caused the car to run very rich, and bypassed the O2 sensor resulting in an open loop situations.

the smoke must have been on the black side then, eh? oil is white/blue.

John,
It was on the black side now that I think back. I'm pretty certain I have to do a top end eventually, but for now it seems to be okay.
Thanks for the interest

Lar

The problems now start. Leave it to those performance chips!

There's always some tradeoff. Wonder whose chip that is?